Shit. Sans feels that guilty stab in his SOUL when Mettaton started to cry. His shoulders sag. He winces. His back still faces the monster in question, and he's quiet for a long time.

"... It did."

He finally looks at Mettaton. It's more like a glance, knowing he'll probably need to go back and forth between words on the floor and Mettaton, but it's more than he's ever done this whole time.

"Does. I'm bad at showing it. Obviously."

No shit, Sherlock, he tells himself.

"I meant... what I said before. That I couldn't figure out if I wanted to help my friend or defend my brother. I was ticked when I said it, but it's still the truth. Goes without saying that I blew it."

... Actually, no. It didn't go without saying. These are things he actually needed to say. Impulse told him otherwise, but you won't believe what a kick in the brain from your brother can do. He looks back at the floor. Papyrus would want him to talk, right?

"That and what you... what you acted like you were doing, it... set off a bad memory."

Now it Sans' turn for his expression to twist. He closes his eyes.

"A long time ago... someone called Papyrus forgettable. And he got..."

...

"... hurt. Really bad."

Sure. That works.

"On top of that, well. You already know about my dad. Anyway. That's not what you were doing. I get it now. I'm not saying this to make me right. I just figured you'd just... want to know why."

A long. slow sigh.

"But you still don't make it easy sometimes."